Question

Musty potato flavour is due to

• A. Ketones
• B. Alkylpyrazines
• C. Aldehydes
• D. Alcohols

Hint:

Microbial Dairy Flavor Defects:
Musty Potato Flavor = ALKYLPYRAZINES (Pseudomonas taetrolens).
Malty Flavor = 3-Methylbutanal (L. lactis biovar maltigenes).
Fruity Flavor = Ethyl butyrate Ethyl hexanoate (P. fragi).

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
Aroma chemistry and psychrotrophic bacterial spoilage of milk: Pseudomonas taetrolens metabolizes amino acids to synthesize volatile methoxy-alkylpyrazines (2-methoxy-3-isopropylpyrazine), producing an intense musty/potato aroma.
Key Formula or Approach:
\[ \text{Metabolism: } \textit{Pseudomonas taetrolens} \longrightarrow \mathbf{2\text{-Methoxy-3-Isopropylpyrazine (Alkylpyrazine)}} \implies \text{Musty Potato Defect} \]

Step 2: Detailed Explanation:
In milk and dairy flavor defect chemistry:
- Musty Potato Flavour Defect in refrigerated fluid milk and cream:
- Caused by the growth of psychrotrophic bacteria, primarily {Pseudomonas taetrolens and Pseudomonas perolens.
- These organisms produce volatile, heterocyclic nitrogen-containing aromatic compounds belonging to the class Alkylpyrazines (specifically 2-methoxy-3-isopropylpyrazine and 2-methoxy-3-isobutylpyrazine) (B).
- Alkylpyrazines have an exceptionally low human olfactory threshold ($< 1 - 2\text{ parts per trillion}$), imparting an unmistakable pungent aroma of raw, earthy, musty potatoes to the milk.

Step 3: Final Answer:
Hence, musty potato flavour is due to Alkylpyrazines, corresponding to option (B).